Orc is the anglicised version of the Sindarin word yrch, the servants of the AinurMelkor. They were most likely created by the perversion of Elves, Melkor being unable to create anything of his own. As such, they shared the immortality of the Elves, but not their appearance. Black, sallow, and stunted, most preferred darkness, however breeds such as the Uruk-Hai were able to endure sunlight.

The orc (or ork) is the classic fantasy punching bag. In many ways, they're treated as little bags filled with gold and experience points. Each system has their own version of this monster (and some have their own version of the spelling).

Dungeons and Dragons, being the grandfather of the games, uses them in the Tolkienesque view, as a race of brutish evil humanoids. Your classic foes whom you can attack without fear of retribution, whom your dungeon master can throw at you in droves without you worrying about the widows and orphans you are creating. As time progressed, they started to allow for some sympathy for the race by allowing you to play a half-orc, but even this was half-hearted as the race was described as the result of an unwilling union between your human mother and a marauding humanoid.

The new Dungeons and Dragons Third Edition has brought back the half-orc, and given a bit more depth to the character. In much the same was as the Klingons from Star Trek, their culture is described as mostly just different. A bit more primitive, but more honest, and not evil. They use scars as marks of pride amongst themselves, they adopt the very Nietschean philosophy of "What does not kill me, makes me stronger," and live in the harshest environments possible. Despite that, in the classic D&D fashion they do have an alignment, and the alignment is Chaotic Evil.

Other games have examined Orks and come up with their own views of them. The Warhammer universe created their own mythology, and called them orks (a very excellent writeup exists in that node.)

Shadowrun and Earthdawn (both by FASA) examined the orc from an even more sympathetic view. (And lump them in with the troll, as the "goblinoid" races. Typically called by the derogative terms "trog" or "troglodyte.") In both games, their strength and their shorter lifespan (venerable orks may live to be 50, but they typically live much shorter lives, and infant mortality is much higher, due to their living conditions), their natural strength, and their unusual looks have put them permanently in the role of "beast of burden" or "thug in the shadows." In Earthdawn, they're a slave race, with no rights. Some have gone rogue and are "scorchers" (basically marauders). And yet some have managed to win their freedom, and create a nation of Orks called Cara Fahd. In Shadowrun, they're not faring much better, forced to live in the slums of the world, only occasionally earning a job as a bouncer or a bodyguard. In this way, they take a role similar to the minority of the 20th century United States of America. (Although, it's the UCAS in Shadowrun.)

Finally, the most sympathetic view of the orc comes from John Wick in Orkworld, who casts them as a race of people connected to the land. Both primitive and innocent, attempting to survive in a shrinking wilderness. The elves, dwarves, and humans in that world are rapidly depleting the resources which the Orks need to survive. In addition, they are killing any Orks they see due to superstitions and fear.

The orc dates back to classical times with Pliny the Elder who described an orc as a sea monster - a 'huge creature armed with teeth.' From this, we get today the Orcinus orca, better known as killer whale.

'Orc' was originally seen in English in the epic poemBeowulf (line 112) as 'orc-neas' which has been translated as demon-corpses or zombies. The singular would be 'orc-thyrs' which was found in Old Norse as 'giant'. There are hints at something even older here with the Old English 'orc' meaning demon being related to the Latin word Orca - meaning "hell" or "death". The Romans considered "Orcus" to be the god of death (the act of death - not to be confused with Hades - the realm of the dead). Orcus was also known as "Mors" (mortal, mortuary,
etc...) or in Greek, "Thantos".

With one of the linguistic shifts that took place from the original Indo-European, what we are familiar with as 'pork' (from French) from 'porcus' (Latin) lost the leading voiceless aspiration of the 'p' and shows up in Gaelic as 'orc'. This may have lead to some of the pig-nature that shows up some renditions of the modern orc.

Many give credit of the orc to Tolkien who pulled the orc from Old English and twisted the name about (as he often did). "Orc" only appears once in The Hobbit. Christopher Tolkien wrote later

GOBLINS Frequently used as alternative term to Orcs (cf. Melko's goblins, the Orcs of the hills 157, but sometimes apparently distinguished, 31, 230)....

Speculation abounds about why Tolkien switched from using "goblin" to "orc". The most reasonable is that goblins were already well known to people as mischievous faeries such as Puck from Midsummer's Night Dream.

Either I mistake your shape and making quite,
Or else you are that shrewd and knavish sprite
Call'd Robin Good-fellow. Are you not he
That frights the maidens of the villagery,
Skims milk, and sometimes labours in the quern,
And bootless makes the breathless housewife churn;
And sometimes makes the drink to bear no barm;
Misleads night-wanderers, laughing at their harm?
Those that Hob-goblin call you, and sweet Puck.
You do their work, and they shall have good luck,
Are not you he?